paper 1B

• Calorimetry is used to determine the Enthalpy Change (ΔH) of a Chemical Reaction. Involves measuring Temperature change in

  a closed system.
• What are the three types of calorimetry?

  Bomb, Coffee cup, and Alcohol Burner with a beaker of water
• Alcohol Burner with a beaker of water involves combusting a solvent or oil in an alcohol burner beneath a beaker of water containing a thermometer or temperature probe.
• Bomb Calorimeter is used for combustion reactions at constant volume and requires specialized equipment where sample is combusted in a sealed metal container in a water bath with temperature change measured with a precise probe
• Coffee Cup Calorimeter is used for reaction processes like neutralization and is carried out in a polystyrene cup with temperature change being recorded by a probe or thermometer

  
• Salt bridge purpose?

  Complete electrical circuit AND maintain electrical neutrality of the solution
• The flow of electrons is ALWAYS

  Anode to Cathode
• The anode is ALWAYS the site of

  oxidation
• The cathode is ALWAYS the site of

  reduction
• The electrolyte in a electrolytic cell is

  a liquid that has high conductivity for molten/aqueous ionic compounds
• A voltaic cell is

  spontaneous and has a voltmeter
• An electrolytic cell is

  non-spontaneous and has a battery
• An electrolytic cell's anode is the

  positive terminal, holding the metal most likely to be reduced
• An electrolytic cell's cathode is the

  negative terminal, holding the metal most likely to be oxidized
• A voltaic cell's anode is the

  negative terminal, holding the metal most likely to be oxidized
• A voltaic cell's cathode is the

  positive terminal, holding the metal most likely to be reduced
• What is one usage of an electrolytic cell?

  Anodizing of Aluminum
• What is another usage of an electrolytic cell?

  Purification of Copper
• What is a third usage of an electrolytic cell?

  Electroplating
• What is the purpose of electroplating?

  • To coat an object with a metal
• What is observed in the purification of copper?

  Impure copper anode erodes and reddish brown copper is deposited onto the cathode

  
• How does electroplating work (+ exceptions)

  Electroplating erodes the anode (containing plating metal) and adds it onto the cathode (object to be plated). Plating metals need to be less reactive than zinc in the reactivity series.

  
• In aqueous electrolytes in electrolytic cells,

  ions compete with water to produce products
• With NaCl, at the cathode,

  water is more likely to produce hydrogen gas as Na is more reactive that likely to be reduced
• With NaCl, at the anode,

  Cl gas is more energetically preferred over water to oxygen but oxygen is still produced when NaCl is in low concentrations
• Primary preparation of a standard solution

  Dilution of a pure sample
• Secondary preparation of a standard solution

  Further dilution of a diluted sample
• For a standard dilution accurate to 1 s.f

  use a measuring cylinder
• For a standard dilution accurate to 2-3 s.f

  use a volumetric flask
• For a standard dilution accurate to 4 s.f

  use specialized equipment with high precision AND a volumetric flask (very hard to achieve)
• When measuring mass

  use the same beaker for all preparations if possible so no mass is lost
• When dissolving solutes

  use much less solvent than is the beaker's capacity to reduce spillage
• When transferring solutions

  always rinse a beaker thoroughly after use
• When measuring

  ensure you are at eye-level with the meniscus
• When solute is not fully dissolved,

  add more solvent, heat the solution slightly, use a magnetic bead to stir the solution, use a sonicator or try a different solvent or pH for the solute
• To prevent contaminates in a solution,

  ensure equipment is clean before use and re-make contaminated solutions
• Primary solution is made using

  volumetric pipette
• Secondary solution is made using

  volumetric flask
• What is the purpose of an acid-base titration?

  To determine the concentration of an unknown acid or base
• What tools are used to detect the endpoint in a titration?

  A pH indicator or a pH meter